After years of denying global warming, physicist Richard Muller now says "global warming is real and humans are almost entirely the cause." The admission by Muller, a professor of physics at the University of California, Berkeley, and founder of the Berkeley Earth Surface Temperature project, has gained additional attention because some of his research has been funded by Charles Koch of the Koch brothers, the right-wing billionaire...

Hundreds of new U.S. counties were declared disaster areas on Wednesday amidst the country’s worst drought in decades. We’re joined by famed environmental activist and 350.org founder Bill McKibben, whose new article for Rolling Stone magazine is called "Global Warming’s Terrifying New Math: Three Simple Numbers that Add Up to Global Catastrophe — And that Make Clear Who the Real Enemy Is." Responding to...

As the U.S. suffers through its worst drought since the 1950s, the author and environmental correspondent Mark Hertsgaard joins us to discuss his new initiative, "Climate Parents." In a new article, "Parents Need to Act Against Climate Change for Their Kids’ Sake," Hertsgaard writes: "Beyond the distress and discomfort, the record-breaking heat raises a puzzling question for anyone who cares about the future of...

See photographs by our guest on Friday, Subhankar Banerjee, which are featured in the new book, "Arctic Voices: Resistance at the Tipping Point" (7 Stories Press). Banerjee is a renowned photographer who spent the past decade working to conserve the Arctic, and raise awareness about indigenous human rights and climate change.

The past two weeks have witnessed the worst forest fires in Colorado history, a deadly Mid-Atlantic storm that left 23 dead and four million without power, and a record shattering heat wave across the East Coast and Midwest that has not seen since the Dust Bowl. More than 2,000 heat records have been broken in the past week. As the words "extreme weather" flash across TV screens, where are the other two words: "global...

As we discuss the spate of extreme weather in the United States, the author and professor Christian Parenti argues that the Republican-led assault on the public sector will leave states more vulnerable to global warming’s effects. "Another thing that’s missing from these discussions is not just the words 'climate change,' but the words 'public sector,'" Parenti says. "I mean, who’s out there...

With extreme weather fueling wildfires in Colorado and record rainfall in Florida, the Obama administration has moved closer to approving construction of the southern section of the Keystone XL pipeline. We’re joined by environmentalist, educator and author Bill McKibben, founder of the grassroots climate campaign 350.org. "Today is one of those days when you understand what the early parts of the global warming era are going to...

As the Rio+20 Earth Summit — the largest U.N. conference ever — ends in disappointment, we’re joined by the leading Canadian scientist, environmentalist and broadcaster, David Suzuki. As host of the long-running CBC program, "The Nature of Things," seen in more than 40 countries, Suzuki has helped educate millions about the rich biodiversity of the planet and the threats it faces from human-driven global warming. In...

On Wednesday, 17-year-old environmental activist Brittany Trilford of Wellington, New Zealand, addressed more than a hundred heads of state at the opening plenary of the Rio+20 U.N. Earth Summit, the largest United Nations gathering ever. "We are all aware that time is ticking, and we are quickly running out," Trilford said. "You have 72 hours to decide the fate of your children, my children, my children’s children. And I...

We’re joined from the Rio+20 Earth Summit in Rio by Nnimmo Bassey, executive director of Environmental Rights Action in Nigeria, chair of Friends of the Earth International. "The leaders came to Rio with, clearly, very low ambitions, and probably with the desire to block agreements on any issue that would not be of particular benefit to them or their countries," Bassey says. "They’ve come out with a draft agreement...